This disclosure relates generally to seals. More particularly, this disclosure relates to brush seals having a sliding backing plate.
Brush seals include wire bristles that extend across seal cavities between a first component and a second component to reduce airflow through the seal cavity. Brush seals typically include a top plate, a backing plate, and a bristle pack extending from between the top plate and the backing plate and across the seal cavity. The backing plate provides support to the bristles to prevent the bristles from deforming. A backing plate gap is formed in the seal cavity between a distal end of the backing plate and the second component that the bristles extend towards and contact. The portion of the bristles extending across the backing plate gap is unsupported, and as such, the bristles can blow over and deform at high pressures and temperatures. However, a relatively large backing plate gap is required in active seal cavities, which are seal cavities where the two components move relative to each other such that the seal cavity expands and contracts during operation, to prevent clashing between the backing plate and the second component. Clashing occurs where the second component contacts the backing plate, and clashing can cause damage to the components defining the seal cavity and to the brush seal.